Methods of reinforcing an intervertebral disc annulus

ABSTRACT

Methods of reinforcing annulus fibrosis tissue within an intervertebral disc include the implantation of a support member also functioning as a barrier to resist damage to the tissue or herniation of tissue outside the disc. The device may be anchored to the surrounding tissue. The device is compressible and may be delivered in a minimally invasive manner through a cannula.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/237,360 filed on Sep. 5, 2002, which is a continuation of U.S.application Ser. No. 09/696,636 filed on Oct. 25, 2000, issued Jan, 21,2003 as U.S. Pat. No. 6,508,839, which is a continuation-in-part of U.S.application Ser. No. 09/642,450 filed on Aug. 18, 2000, issued Nov. 19,2002 as U.S. Pat. No. 6,482,235, which is a continuation-in-part of U.S.application Ser. No. 09/608,797 filed on Jun. 30, 2000, issued Jul. 30,2002 as U.S. Pat. No. 6,425,919, wherein U.S. application Ser. No.09/608,797 claims benefit to U.S. Provisional Application No. 60/149,490filed Aug. 18, 1999, U.S. Provisional Application No. 60/161,085 filedOct. 25, 1999 and U.S. Provisional Application No. 60/172,996 filed Dec.21, 1999 the contents of each of which are incorporated in theirentirety into this disclosure by reference.

BACKGROUND OF THE INVENTION

The present invention relates to the surgical treatment ofintervertebral discs in the lumbar, cervical, or thoracic spine thathave suffered from tears in the annulus fibrosis, herniation of thenucleus pulposus and/or significant disc height loss.

The disc performs the important role of absorbing mechanical loads whileallowing for constrained flexibility of the spine. The disc is composedof a soft, central nucleus pulposus (NP) surrounded by a tough, wovenannulus fibrosis (AF). Herniation is a result of a weakening in the AF.Symptomatic herniations occur when weakness in the AF allows the NP tobulge or leak posteriorly toward the spinal cord and major nerve roots.The most common resulting symptoms are pain radiating along a compressednerve and low back pain, both of which can be crippling for the patient.The significance of this problem is increased by the low average age ofdiagnosis, with over 80% of patients in the U.S. being under 59.

Since its original description by Mixter & Barr in 1934, discectomy hasbeen the most common surgical procedure for treating intervertebral discherniation. This procedure involves removal of disc materials impingingon the nerve roots or spinal cord external to the disc, generallyposteriorly. Depending on the surgeon's preference, varying amounts ofNP are then removed from within the disc space either through theherniation site or through an incision in the AF. This removal of extraNP is commonly done to minimize the risk of recurrent herniation.

Nevertheless, the most significant drawbacks of discectomy arerecurrence of herniation, recurrence of radicular symptoms, andincreasing low back pain. Re-herniation can occur in up to 21% of cases.The site for re-herniation is most commonly the same level and side asthe previous herniation and can occur through the same weakened site inthe AF. Persistence or recurrence of radicular symptoms happens in manypatients and when not related to re-herniation, tends to be linked tostenosis of the neural foramina caused by a loss in height of theoperated disc. Debilitating low back pain occurs in roughly 14% ofpatients. All of these failings are most directly related to the loss ofNP material and AF competence that results from herniation and surgery.

Loss of NP material deflates the disc, causing a decrease in discheight. Significant decreases in disc height have been noted in up to98% of operated patients. Loss of disc height increases loading on thefacet joints. This can result in deterioration of facet cartilage andultimately osteoarthritis and pain in this joint. As the joint spacedecreases the neural foramina formed by the inferior and superiorvertebral pedicles also close down. This leads to foraminal stenosis,pinching of the traversing nerve root, and recurring radicular pain.Loss of NP also increases loading on the remaining AF, a partiallyinnervated structure that can produce pain. Finally, loss of NP resultsin greater bulging of the AF under load. This can result in renewedimpingement by the AF on nerve structures posterior to the disc.

Persisting tears in the AF that result either from herniation orsurgical incision also contribute to poor results from discectomy. TheAF has limited healing capacity with the greatest healing occurring inits outer borders. Healing takes the form of a thin fibrous film thatdoes not approach the strength of the uninjured disc. Surgical incisionin the AF has been shown to produce immediate and long lasting decreasesin stiffness of the AF particularly against torsional loads. This mayover-stress the facets and contribute to their deterioration. Further,in as many as 30% of cases, the AF never closes. In these cases, notonly is re-herniation a risk but also leakage of fluids or solids fromwithin the NP into the epidural space can occur. This has been shown tocause localized pain, irritation of spinal nerve roots, decreases innerve conduction velocity, and may contribute to the formation ofpost-surgical scar tissue in the epidural space.

Other orthopedic procedures involving removal of soft tissue from ajoint to relieve pain have resulted in significant, long lastingconsequences. Removal of all or part of the menisci of the knee is oneexample. Partial and total meniscectomy leads to increasedosteoarthritic degeneration in the knee and the need for further surgeryin many patients. A major effort among surgeons to repair rather thanresect torn menisci has resulted in more durable results and lessenedjoint deterioration.

Systems and methods for repairing tears in soft tissues are known in theart. One such system relates to the repair of the menisci of the kneeand is limited to a barbed tissue anchor, an attached length of suture,and a suture-retaining member, which can be affixed to the suture andused to draw the sides of a tear into apposition. The drawback of thismethod is that it is limited to the repair of a tear in soft tissue. Inthe intervertebral disc, closure of a tear in the AF does notnecessarily prevent further bulging of that disc segment toward theposterior neural elements. Further, there is often no apparent tear inthe AF when herniation occurs. Herniation can be a result of a generalweakening in the structure of the AF (soft disc) that allows it to bulgeposteriorly without a rupture. When tears do occur, they are oftenradial.

Another device known in the art is intended for repair of a tear in apreviously contiguous soft tissue. Dart anchors are placed across thetear in a direction generally perpendicular to the plane of the tear.Sutures leading from each of at least two anchors are then tied togethersuch that the opposing sides of the tear are brought together. However,all of the limitations pertaining to repair of intervertebral discs, asdescribed above, pertain to this device.

Also known in the art is an apparatus and method of using tension toinduce growth of soft tissue. The known embodiments and methods arelimited in their application to hernias of the intervertebral disc inthat they require a spring to apply tension. Aside from the difficultyof placing a spring within the limited space of the intervertebral disc,a spring will induce a continuous displacement of the attached tissuesthat could be deleterious to the structure and function of the disc. Aspring may further allow a posterior bulge in the disc to progressshould forces within the disc exceed the tension force applied by thespring. Further, the known apparatus is designed to be removed once thedesired tissue growth has been achieved. This has the drawback ofrequiring a second procedure.

There are numerous ways of augmenting the intervertebral disc disclosedin the art. In reviewing the art, two general approaches areapparent—implants that are fixed to surrounding tissues and those thatare not fixed, relying instead on the AF to keep them in place.

The first type of augmenting of the intervertebral disc includesgenerally replacing the entire disc. This augmentation is limited inmany ways. First, by replacing the entire disc, they generally mustendure all of the loads that are transferred through that disc space.Many degenerated discs are subject to pathologic loads that exceed thosein normal discs. Hence, the designs must be extremely robust and yetflexible. None of these augmentation devices has yet been able toachieve both qualities. Further, devices that replace the entire discmust be implanted using relatively invasive procedures, normally from ananterior approach. They may also require the removal of considerableamounts of healthy disc material including the anterior AF. Further, thedisclosed devices must account for the contour of the neighboringvertebral bodies to which they are attached. Because each patient andeach vertebra is different, these types of implants must be available inmany shapes and sizes.

The second type of augmentation involves an implant that is not directlyfixed to surrounding tissues. These augmentation devices rely on an AFthat is generally intact to hold them in place. The known implants aregenerally inserted through a hole in the AF and either expand, areinflated, or deploy expanding elements so as to be larger than the holethrough which they are inserted. The limitation of these concepts isthat the AF is often not intact in cases requiring augmentation of thedisc. There are either rents in the AF or structural weaknesses thatallow herniation or migration of the disclosed implants. In the case ofa disc herniation, there are definite weaknesses in the AF that allowedthe herniation to occur. Augmenting the NP with any of the knownaugmentation devices without supporting the AF or implant risksre-herniation of the augmenting materials. Further, those devices withdeployable elements risk injuring the vertebral endplates or the AF.This may help to retain the implant in place, but again herniations donot require a rent in the AF. Structural weakness in or delamination ofthe multiple layers of the AF can allow these implants to bulge towardthe posterior neural elements. Additionally, as the disc continues todegenerate, rents in the posterior annulus may occur in regions otherthan the original operated site. A further limitation of these conceptsis that they require the removal of much or all of the NP to allowinsertion of the implant. This requires time and skill to achieve andpermanently alters the physiology of the disc.

Implanting prostheses in specific locations within the intervertebraldisc is also a challenging task. The interior of the disc is not visibleto the surgeon during standard posterior spinal procedures. Very littleof the exterior of the disc can be seen through the small window createdby the surgeon in the posterior elements of the vertebrae to gain accessto the disc. The surgeon further tries to minimize the size of anyannular fenestration into the disc in order to reduce the risk ofpostoperative herniation and/or further destabilization of the operatedlevel. Surgeons generally open only one side of the posterior annulus inorder to avoid scarring on both sides of the epidural space.

The rigorous requirements presented by these limitations on access toand visualization of the disc are not well compensated for by any of theintradiscal prosthesis implantation systems currently available.

The known art relating to the closure of body defects such as herniasthrough the abdominal wall involve devices such as planer patchesapplied to the interior of the abdominal wall or plugs that are placeddirectly into the defect. The known planar patches are limited in theirapplication in the intervertebral disc by the disc's geometry. Theinterior aspect of the AF is curved in multiple planes, making a flatpatch incongruous to the surface against which it must seal. Finally,the prior art discloses patches that are placed into a cavity that iseither distended by gas or supported such that the interior wall of thedefect is held away from internal organs. In the disc, it is difficultto create such a cavity between the inner wall of the annulus and the NPwithout removing nucleus material. Such removal may be detrimental tothe clinical outcome of disc repair.

One hernia repair device known in the art is an exemplary plug. Thisplug may be adequate for treating inguinal hernias, due to the lowpressure difference across such a defect. However, placing a plug intothe AF that must resist much higher pressures may result in expulsion ofthe plug or dissection of the inner layers of the annulus by the NP.Either complication would lead to extraordinary pain or loss of functionfor the patient. Further, a hernia in the intervertebral disc is likelyto spread as the AF progressively weakens. In such an instance, the plugmay be expelled into the epidural space.

Another hernia repair device involves a curved prosthetic mesh for usein inguinal hernias. The device includes a sheet of material that has aconvex side and a concave side and further embodiments with bothspherical and conical sections. This device may be well suited foringuinal hernias, but the shape and stiffness of the disclosedembodiments are less than optimal for application in hernias of theintervertebral disc. Hernias tend to be broader (around thecircumference of the disc) than they are high (the distance between theopposing vertebrae), a shape that does not lend itself to closure bysuch conical or spherical patches.

Another device involves an inflatable, barbed balloon patch used forclosing inguinal hernias. This balloon is left inflated within thedefect. A disadvantage of this device is that the balloon must remaininflated for the remainder of the patient's life to insure closure ofthe defect. Implanted, inflated devices rarely endure long periodswithout leaks, particularly when subjected to high loads. This is trueof penile prostheses, breast implants, and artificial sphincters.

Another known method of closing inguinal hernias involves applying bothbeat and pressure to a planar patch and the abdominal wall surroundingthe hernia. This method has the drawback of relying entirely on theintegrity of the wall surrounding the defect to hold the patch in place.The annulus is often weak in areas around a defect and may not serve asa suitable anchoring site. Further, the planar nature of the patch hasall of the weaknesses discussed above.

Various devices and techniques have further been disclosed for sealingvascular puncture sites. The most relevant is a hemostaticpuncture-sealing device that generally consists of an anchor, a filamentand a sealing plug. The anchor is advanced into a vessel through adefect and deployed such that it resists passage back through thedefect. A filament leading from the anchor and through the defect can beused to secure the anchor or aid in advancing a plug that is broughtagainst the exterior of the defect. Such a filament, if it were toextend to the exterior of the disc, could lead to irritation of nerveroots and the formation of scar tissue in the epidural space. This isalso true of any plug material that may be left either within the defector extending to the exterior of the disc. Additionally, such devices andmethods embodied for use in the vascular system require a spacerelatively empty of solids for the deployment of the interior anchor.This works well on the interior of a vessel, however, in the presence ofthe more substantial NP, the disclosed internal anchors are unlikely toorient across the defect as disclosed in their inventions.

SUMMARY OF THE INVENTION

It is an object of the disclosed invention to reduce the long-termnegative consequences of back injuries such as herniated discs byrepairing and/or augmenting rather than resecting the soft tissues ofthe disc. It is a further object of this invention to prevent or reducethe occurrence of re-hemiation and disc height loss following surgicaltherapy for herniated discs. It is a further object of this invention toincrease the AF's resistance to posterior bulging and leakage of NPmaterial while preferably increasing its stiffness under load. It is afurther object of this invention to permit the augmentation of the softtissues of the disc in such a way so as to limit the risk of theherniation of any augmentation materials toward nerve structuresposterior to the disc. It is a further object of the present inventionto shield the sensitive nerve fibers in the outer layers of the annulusfrom pressures within the nucleus.

In one aspect of the present invention there is provided an in vivoaugmented functional spine unit. The augmented functional spine unitincludes the two adjoining vertebrae and the intervertebral disc,composed of a central region surrounded by an annulus fibrosis andsituated in the intervertebral disc space between the vertebra, and adisc herniation constraining device situated within the intervertebraldisc space. The disc herniation constraining device includes an anchorfixedly coupled to an anterior portion of one of the adjoining vertebraeor annulus fibrosis and is connected to a support member by a connectingmember. The support member is positioned posterior to the centralregion, preferably in or posterior to the annulus fibrosis. In oneembodiment the central region of the functional spine unit contains anucleus pulposus.

In another embodiment of the invention, the connection member ismaintained under tension between the anchor and the support member. Inyet another embodiment, augmentation material is secured along at leasta portion of the length of the connection member, which serves to assistthe function of the intervertebral disc in supporting and separating thevertebrae, and allowing motion of one vertebra relative to the other.

In another aspect of the invention there is provided an in vivoaugmented functional spine unit. The augmented functional spine unitincludes the two adjoining vertebrae and the intervertebral disc,composed of a central region surrounded by an annulus fibrosis andsituated in the intervertebral disc space between the vertebra, and adisc augmentation device situated within the intervertebral disc space.The disc augmentation device includes an anchor fixedly coupled to ananterior portion of one of the adjoining vertebrae or annulus fibrosis,augmentation material situated in the intervertebral disc space andrestrained therein by a connection member secured between the anchor andthe augmentation material. In an alternate embodiment, a support memberis secured within the functional spine unit, the connection memberextends between the anchor, the augmentation material and the supportmember, further restraining the movement of the augmentation materialwithin the central region. In yet another embodiment, the central regionmay contain a nucleus pulposus.

In yet another aspect of the present invention there are providedmethods of augmenting a functional spine unit. These methods includeusing the disc herniation constraining devices and the disc augmentationdevices disclosed herein.

The present invention further relates to devices and methods for sealingdefects in tissue walls separating two anatomic regions of the body.Specifically, prosthetic devices and methods are disclosed which allowthe closure of a defect in the AF of the human intervertebral disc,preventing the egress of material from within the disc and/ordistributing pressure within the disc space across an inner wall surfaceof the disc.

Closure of the defect is achieved by placing a membrane or barrier on aninterior aspect of the defect. In the case of the intervertebral disc,the barrier is positioned either on the interior aspect of the AFproximate to the NP or between layers of the AF. The barrier means maybe inserted by dissecting a space between the annulus and nucleus.Alternatively, a portion of the nucleus and/or annulus may be resectedto create adequate space.

The barrier may be inserted into position directly through the defect oralternatively it may be advanced from a remote entry through the tissuewall or other tissue neighboring the defect.

Various fixation devices can be used to secure the barrier tosurrounding tissues. In the intervertebral disc, these tissues caninclude the surrounding AF, vertebral endplates, vertebral bodies, andeven NP. Alternatively, the barrier can be held in place simply by thepressure the NP exerts on the barrier and AF where the stiffness andshape of the barrier patch may also help to maintain position andorientation within the disc. The barrier may further incorporate variousself-retaining members that resist motion of the barrier within thedisc. The barrier or membrane may incorporate a frame that can serve toenlarge or expand the dimensions of the barrier from a compressed stateto an enlarged state. The frame can be a self expanding material such asa nickel titanium material. The barrier may further have properties thatcause it to adhere to surrounding tissues either with an adhesive, bythe application of heat, or ingrowth/ongrowth of surrounding tissue.Various embodiments of the disclosed barrier are composed of eithersingular materials and components or a multiplicity of materials andcomponents.

It is a further object of the present invention to reduce thelimitations of current disc repair methods. It is a further object ofthe present invention to provide systems and methods for implanting aprosthesis along the interior aspect of the annulus through a single,small annulotomy from the posterior aspect of the disc.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1A shows a transverse section of a portion of a functional spineunit, in which part of a vertebra and intervertebral disc are depicted.

FIG. 1B shows a sagittal cross section of a portion of a functionalspine unit shown in FIG. 1A, in which two lumbar vertebrae and theintervertebral disc are visible.

FIG. 1C shows partial disruption of the inner layers of an annulusfibrosis.

FIG. 2A shows a transverse section of one aspect of the presentinvention prior to supporting a herniated segment.

FIG. 2B shows a transverse section of the construct in FIG. 2Asupporting the herniated segment.

FIG. 3A shows a transverse section of another embodiment of thedisclosed invention after placement of the device.

FIG. 3B shows a transverse section of the construct in FIG. 3A aftertension is applied to support the herniated segment.

FIG. 4A shows a transverse view of an alternate embodiment of theinvention.

FIG. 4B shows a sagittal view of the alternate embodiment shown in FIG.4A.

FIG. 5A shows a transverse view of another aspect of the presentinvention.

FIG. 5B shows the delivery tube of FIG. 5A being used to displace theherniated segment to within its pre-herniated borders.

FIG. 5C shows a one-piece embodiment of the invention in an anchored andsupporting position.

FIG. 6 shows one embodiment of the invention supporting a weakenedposterior annulus fibrosis.

FIG. 7A shows a transverse section of another aspect of the disclosedinvention demonstrating two stages involved in augmentation of the softtissues of the disc.

FIG. 7B shows a sagittal view of the invention shown in FIG. 7A.

FIG. 8 shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc andsupport/closure of the annulus fibrosis.

FIG. 9A shows a transverse section of one aspect of the inventioninvolving augmentation of the soft tissues of the disc with the flexibleaugmentation material anchored to the anterior lateral annulus fibrosis.

FIG. 9B shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc withthe flexible augmentation material anchored to the annulus fibrosis by aone-piece anchor.

FIG. 10A shows a transverse section of one aspect of the disclosedinvention involving augmentation of the soft tissues of the disc.

FIG. 10B shows the construct of FIG. 10A after the augmentation materialhas been inserted into the disc.

FIG. 11 illustrates a transverse section of a barrier mounted within anannulus.

FIG. 12 shows a sagittal view of the barrier of FIG. 11.

FIG. 13 shows a transverse section of a barrier anchored within a disc.

FIG. 14 illustrates a sagittal view of the barrier shown in FIG. 13.

FIG. 15 illustrates the use of a second anchoring device for a barriermounted within a disc.

FIG. 16A is an transverse view of the intervertebral disc.

FIG. 16B is a sagittal section along the midline of the intervertebraldisc.

FIG. 17 is an axial view of the intervertebral disc with the right halfof a sealing means of a barrier means being placed against the interioraspect of a defect in annulus fibrosis by a dissection/delivery tool.

FIG. 18 illustrates a full sealing means placed on the interior aspectof a defect in annulus fibrosis.

FIG. 19 depicts the sealing means of FIG. 18 being secured to tissuessurrounding the defect.

FIG. 20 depicts the sealing means of FIG. 19 after fixation means havebeen passed into surrounding tissues.

FIG. 21A depicts an axial view of the sealing means of FIG. 20 havingenlarging means inserted into the interior cavity.

FIG. 21B depicts the construct of FIG. 21 in a sagittal section.

FIG. 22A shows an alternative fixation scheme for the sealing means andenlarging means.

FIG. 22B shows the construct of FIG. 22A in a sagittal section with ananchor securing a fixation region of the enlarging means to a superiorvertebral body in a location proximate to the defect.

FIG. 23A depicts an embodiment of the barrier means of the presentinvention being secured to an annulus using fixation means.

FIG. 23B depicts an embodiment of the barrier means of FIG. 23A securedto an annulus by two fixation darts wherein the fixation tool has beenremoved.

FIGS. 24A and 24B depict a barrier means positioned between layers ofthe annulus fibrosis on either side of a defect.

FIG. 25 depicts an axial cross section of a large version of a barriermeans.

FIG. 26 depicts an axial cross section of a barrier means in positionacross a defect following insertion of two augmentation devices.

FIG. 27 depicts the barrier means as part of an elongated augmentationdevice.

FIG. 28A depicts an axial section of an alternate configuration of theaugmentation device of FIG. 27.

FIG. 28B depicts a sagittal section of an alternate configuration of theaugmentation device of FIG. 27.

FIGS. 29A D depict deployment of a barrier from an entry site remotefrom the defect in the annulus fibrosis.

FIGS. 30A, 30B, 31A, 31B, 32A, 32B, 33A, and 33B depict axial andsectional views, respectively, of various embodiments of the barrier.

FIG. 34A shows a non-axisymmetric expansion means or frame.

FIGS. 34B and 34C illustrate perspective views of a frame mounted withinan intervertebral disc.

FIGS. 35 and 36 illustrate alternate embodiments of the expansion meansshown in FIG. 34.

FIGS. 37A-C illustrate a front, side, and perspective view,respectively, of an alternate embodiment of the expansion means shown inFIG. 34.

FIG. 38 shows an alternate expansion means to that shown in FIG. 37A.

FIGS. 39A-D illustrate a tubular expansion means having a circularcross-section.

FIGS. 40A-D illustrate a tubular expansion means having an oval shapedcross-section.

FIGS. 40E, 40F and 40I illustrate a front, back and top view,respectively of the tubular expansion means of FIG. 40A having a sealingmeans covering an exterior surface of an annulus face.

FIGS. 40G and 40H show the tubular expansion means of FIG. 40A having asealing means covering an interior surface of an annulus face.

FIGS. 41A-D illustrate a tubular expansion means having an egg-shapedcross-section.

FIG. 42A-D depicts cross sections of a preferred embodiment of sealingand enlarging means.

FIGS. 43A and 43B depict an alternative configuration of enlargingmeans.

FIGS. 44A and 44B depict an alternative shape of the barrier means.

FIG. 45 is a section of a device used to affix scaling means to tissuessurrounding a defect.

FIG. 46 depicts the use of a thermal device to heat and adhere sealingmeans to tissues surrounding a defect.

FIG. 47 depicts an expandable thermal element that can be used to adheresealing means to tissues surrounding a defect.

FIG. 48 depicts an alternative embodiment to the thermal device of FIG.46.

FIGS. 49A-G illustrate a method of implanting an intradiscal implant.

FIGS. 50A-F show an alternate method of implanting an intradiscalimplant.

FIGS. 51A-C show another alternate method of implanting an intradiscalimplant.

FIGS. 52A and 52B illustrate an implant guide used with the intradiscalimplant system.

FIG. 53A illustrates a barrier having stiffening plate elements.

FIG. 53B illustrates a sectional view of the barrier of FIG. 53A.

FIG. 54A shows a stiffening plate.

FIG. 54B shows a sectional view of the stiffening plate of FIG. 54A.

FIG. 55A illustrates a barrier having stiffening rod elements.

FIG. 55B illustrates a sectional view of the barrier of FIG. 55A.

FIG. 56A illustrates a stiffening rod.

FIG. 56B illustrates a sectional view of the stiffening rod of FIG. 56A.

FIG. 57 shows an alternate configuration for the location of thefixation devices of the barrier of FIG. 44A.

FIGS. 58A and 58B illustrate a dissection device for an intervertebraldisc.

FIGS. 59A and 59B illustrate an alternate dissection device for anintervertebral disc.

FIGS. 60A-C illustrate a dissector component.

FIGS. 61A-D illustrate a method of inserting a disc implant within anintervertebral disc.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for an in vivo augmented functional spineunit. A functional spine unit includes the bony structures of twoadjacent vertebrae (or vertebral bodies), the soft tissue (annulusfibrosis (AF), and optionally nucleus pulposus (NP)) of theintervertebral disc, and the ligaments, musculature and connectivetissue connected to the vertebrae. The intervertebral disc issubstantially situated in the intervertebral space formed between theadjacent vertebrae. Augmentation of the functional spine unit caninclude repair of a herniated disc segment, support of a weakened, tornor damaged annulus fibrosis, or the addition of material to orreplacement of all or part of the nucleus pulposus. Augmentation of thefunctional spine unit is provided by herniation constraining devices anddisc augmentation devices situated in the intervertebral disc space.

FIGS. 1A and 1B show the general anatomy of a functional spine unit 45.In this description and the following claims, the terms ‘anterior’ and‘posterior’, 'superior’ and ‘inferior’ are defined by their standardusage in anatomy, i.e., anterior is a direction toward the front(ventral) side of the body or organ, posterior is a direction toward theback (dorsal) side of the body or organ; superior is upward (toward thehead) and inferior is lower (toward the feet).

FIG. 1A is an axial view along the transverse axis M of a vertebral bodywith the intervertebral disc 15 superior to the vertebral body. Axis Mshows the anterior (A) and posterior (P) orientation of the functionalspine unit within the anatomy. The intervertebral disc 15 contains theannulus fibrosis (AF) 10 which surrounds a central nucleus pulposus (NP)20. A Herniated segment 30 is depicted by a dashed-line. The herniatedsegment 30 protrudes beyond the pre-herniated posterior border 40 of thedisc. Also shown in this figure are the left 70 and right 70′ transversespinous processes and the posterior spinous process 80.

FIG. 1B is a sagittal section along sagittal axis N through the midlineof two adjacent vertebral bodies 50 (superior) and 50′ (inferior).Intervertebral disc space 55 is formed between the two vertebral bodiesand contains intervertebral disc 15, which supports and cushions thevertebral bodies and permits movement of the two vertebral bodies withrespect to each other and other adjacent functional spine units.

Intervertebral disc 15 is comprised of the outer AF 10 which normallysurrounds and constrains the NP 20 to be wholly within the borders ofthe intervertebral disc space. In FIGS. 1A and 1B, herniated segment 30,represented by the dashed-line, has migrated posterior to thepre-herniated border 40 of the posterior AF of the disc. Axis M extendsbetween the anterior (A) and posterior (P) of the functional spine unit.The vertebral bodies also include facet joints 60 and the superior 90and inferior 90′ pedicle that form the neural foramen 100. Disc heightloss occurs when the superior vertebral body 50 moves inferiorlyrelative to the inferior vertebral body 50′.

Partial disruption 121 of the inner layers of the annulus 10 without atrue perforation has also been linked to chronic low back pain. Such adisruption 4 is illustrated in FIG. 1C. It is thought that weakness ofthese inner layers forces the sensitive outer annular lamellae to endurehigher stresses. This increased stress stimulates the small nerve fiberspenetrating the outer annulus, which results in both localized andreferred pain.

In one embodiment of the present invention, the disc herniationconstraining devices 13 provide support for returning all or part of theherniated segment 30 to a position substantially within itspre-herniated borders 40. The disc herniation constraining deviceincludes an anchor which is positioned at a site within the functionalspine unit, such as the superior or inferior vertebral body, or theanterior medial, or anterior lateral annulus fibrosis. The anchor isused as a point against which all or part of the herniated segment istensioned so as to return the herniated segment to its pre-herniatedborders, and thereby relieve pressure on otherwise compressed neuraltissue and structures. A support member is positioned in or posterior tothe herniated segment, and is connected to the anchor by a connectingmember. Sufficient tension is applied to the connecting member so thatthe support member returns the herniated segment to a pre-herniatedposition. In various embodiments, augmentation material is securedwithin the intervertebral disc space, which assists the NP in cushioningand supporting the inferior and superior vertebral bodies. An anchorsecured in a portion of the functional spine unit and attached to theconnection member and augmentation material limits movement of theaugmentation material within the intervertebral disc space. A supportingmember, located opposite the anchor, may optionally provide a secondpoint of attachment for the connection member and further hinder themovement of the augmentation material within the intervertebral discspace.

FIGS. 2A and 2B depict one embodiment of device 13. FIG. 2A shows theelements of the constraining device in position to correct the herniatedsegment. Anchor is securely established in a location within thefunctional spine unit, such as the anterior AF shown in the figure.Support member 2 is positioned in or posterior to herniated segment 30.Leading from and connected to anchor 1 is connection member 3, whichserves to connect anchor 1 to support member 2. Depending on thelocation chosen for support member 2, the connection member may traversethrough all or part of the herniated segment.

FIG. 2B shows the positions of the various elements of the herniationconstraining device 13 when the device 13 is supporting the herniatedsegment. Tightening connection member 2 allows it to transmit tensileforces along its length, which causes herniated segment 30 to moveanteriorly, i.e., in the direction of its pre-herniated borders. Onceherniated segment 30 is in the desired position, connection member 3 issecured in a permanent fashion between anchor 1 and support member 2.This maintains tension between anchor 1 and support member 2 andrestricts motion of the herniated segment to within the pre-herniatedborders 40 of the disc. Support member 2 is used to anchor to herniatedsegment 30, support a weakened AF in which no visual evidence ofherniation is apparent, and may also be used to close a defect in the AFin the vicinity of herniated segment 30.

Anchor 1 is depicted in a representative form, as it can take one ofmany suitable shapes, be made from one of a variety of biocompatiblematerials, and be constructed so as to fall within a range of stiffness.It can be a permanent device constructed of durable plastic or metal orcan be made from a resorbable material such as polylactic acid (PLA) orpolyglycolic acid (PGA). Specific embodiments are not shown, but manypossible designs would be obvious to anyone skilled in the art.Embodiments include, but are not limited to, a barbed anchor made of PLAor a metal coil that can be screwed into the anterior AF. Anchor 1 canbe securely established within a portion of the functional spine unit inthe usual and customary manner for such devices and locations, such asbeing screwed into bone, sutured into tissue or bone, or affixed totissue or bone using an adhesive method, such as cement, or othersuitable surgical adhesives. Once established within the bone or tissue,anchor 1 should remain relatively stationary within the bone or tissue.

Support member 2 is also depicted in a representative format and sharesthe same flexibility in material and design as anchor 1. Both deviceelements can be of the same design, or they can be of different designs,each better suited to being established in healthy and diseased tissuerespectively. Alternatively, in other forms, support member 2 can be acap or a bead shape, which also serves to secure a tear or puncture inthe AF, or it can be bar or plate shaped, with or without barbs tomaintain secure contact with the herniated segment. Support member 2 canbe established securely to, within, or posterior to the herniatedsegment.

The anchor and support member can include suture, bone anchors, softtissue anchors, tissue adhesives, and materials that support tissueingrowth although other forms and materials are possible. They may bepermanent devices or resorbable. Their attachment to a portion of FSUand herniated segment must be strong enough to resist the tensionalforces that result from repair of the hernia and the loads generatedduring daily activities.

Connection member 3 is also depicted in representative fashion. Member 3may be in the format of a flexible filament, such as a single ormulti-strand suture, wire, or perhaps a rigid rod or broad band ofmaterial, for example. The connection member can further include suture,wire, pins, and woven tubes or webs of material. It can be constructedfrom a variety of materials, either permanent or resorbable, and can beof any shape suitable to fit within the confines of the intervertebraldisc space. The material chosen is preferably adapted to be relativelystiff while in tension, and relatively flexible against all other loads.This allows for maximal mobility of the herniated segment relative tothe anchor without the risk of the supported segment moving outside ofthe pre-herniated borders of the disc. The connection member may be anintegral component of either the anchor or support member or a separatecomponent. For example, the connection member and support member couldbe a length of non-resorbing suture that is coupled to an anchor,tensioned against the anchor, and sewn to the herniated segment.

FIGS. 3A and 3B depict another embodiment of device 13. In FIG. 3A theelements of the herniation constraining device are shown in positionprior to securing a herniated segment. Anchor 1 is positioned in the AFand connection member 3 is attached to anchor 1. Support member 4 ispositioned posterior to the posterior-most aspect of herniated segment30. In this way, support member 4 does not need to be secured inherniated segment 30 to cause herniated segment 30 to move within thepre-herniated borders 40 of the disc. Support member 4 has the sameflexibility in design and material as anchor 1, and may further take theform of a flexible patch or rigid plate or bar of material that iseither affixed to the posterior aspect of herniated segment 30 or issimply in a form that is larger than any hole in the AF directlyanterior to support member 4. FIG. 3B shows the positions of theelements of the device when tension is applied between anchor 1 andsupport member 4 along connection member 3. The herniated segment isdisplaced anteriorly, within the pre-herniated borders 40 of the disc.

FIGS. 4A and 4B show five examples of suitable anchoring sites withinthe FSU for anchor 1. FIG. 4A shows an axial view of anchor 1 in variouspositions within the anterior and lateral AF. FIG. 4B similarly shows asagittal view of the various acceptable anchoring sites for anchor 1.Anchor 1 is secured in the superior vertebral body 50, inferiorvertebral body 50′ or anterior AF 10, although any site that canwithstand the tension between anchor 1 and support member 2 alongconnection member 3 to support a herniated segment within itspre-herniated borders 40 is acceptable.

Generally, a suitable position for affixing one or more anchors is alocation anterior to the herniated segment such that, when tension isapplied along connection member 3, herniated segment 30 is returned to asite within the pre-herniated borders 40. The site chosen for the anchorshould be able to withstand the tensile forces applied to the anchorwhen the connection member is brought under tension. Because mostsymptomatic herniations occur in the posterior or posterior lateraldirections, the preferable site for anchor placement is anterior to thesite of the herniation. Any portion of the involved FSU is generallyacceptable, however the anterior, anterior medial, or anterior lateralAF is preferable. These portions of the AF have been shown to haveconsiderably greater strength and stiffness than the posterior orposterior lateral portions of the AF. As shown in FIGS. 4A and 4B,anchor 1 can be a single anchor in any of the shown locations, or therecan be multiple anchors 1 affixed in various locations and connected toa support member 2 to support the herniated segment. Connection member 3can be one continuous length that is threaded through the sited anchorsand the support member, or it can be several individual strands ofmaterial each terminated under tension between one or more anchors andone or more support members.

In various forms of the invention, the anchor(s) and connectionmember(s) may be introduced and implanted in the patient, with theconnection member under tension. Alternatively, those elements may beinstalled, without introducing tension to the connection member, butwhere the connection member is adapted to be under tension when thepatient is in a non-horizontal position, i.e., resulting from loading inthe intervertebral disc.

FIGS. 5A-C show an alternate embodiment of herniation constrainingdevice 13A. In this series of figures, device 13A, a substantiallyone-piece construct, is delivered through a delivery tube 6, althoughdevice 13A could be delivered in a variety of ways including, but notlimited to, by hand or by a hand held grasping instrument. In FIG. 5A,device 13A in delivery tube 6 is positioned against herniated segment30. In FIG. 5B, the herniated segment is displaced within itspre-herniated borders 40 by device 13A and/or delivery tube 6 such thatwhen, in FIG. 5C, device 13A has been delivered through delivery tube 6,and secured within a portion of the FSU, the device supports thedisplaced herniated segment within its pre-herniated border 40.Herniation constraining device 13A can be made of a variety of materialsand have one of many possible forms so long as it allows support of theherniated segment 30 within the pre-herniated borders 40 of the disc.Device 13A can anchor the herniated segment 30 to any suitable anchoringsite within the FSU, including, but not limited to the superiorvertebral body, inferior vertebral body, or anterior AF. Device 133A maybe used additionally to close a defect in the AF of herniated segment30. Alternatively, any such defect may be left open or may be closedusing another means.

FIG. 6 depicts the substantially one-piece device 13A supporting aweakened segment 30′ of the posterior AF 10′. Device 13A is positionedin or posterior to the weakened segment 30′ and secured to a portion ofthe FSU, such as the superior vertebral body 50, shown in the figure, orthe inferior vertebral body 50′ or anterior or anterior-lateral annulusfibrosis 10. In certain patients, there may be no obvious herniationfound at surgery. However, a weakened or tom AF that may not beprotruding beyond the pre-herniated borders of the disc may still inducethe surgeon to remove all or part of the NP in order to decrease therisk of herniation. As an alternative to discectomy, any of theembodiments of the invention may be used to support and perhaps closedefects in weakened segments of AF.

A further embodiment of the present invention involves augmentation ofthe soft tissues of the intervertebral disc to avoid or reverse discheight loss. FIGS. 7A and 7B show one embodiment of device 13 securingaugmentation material in the intervertebral disc space 55. In the leftside of FIG. 7A, anchors 1 have been established in the anterior AF 10.Augmentation material 7 is in the process of being inserted into thedisc space along connection member 3 which, in this embodiment, haspassageway 9. Support member 2′ is shown ready to be attached toconnection member 3 once the augmentation material 7 is properlysituated. In this embodiment, connection member 3 passes through anaperture 11 in support member 2′, although many other methods ofaffixing support member 2′ to connection member 3 are possible andwithin the scope of this invention.

Augmentation material 7 may have a passageway 9, such as a channel, slitor the like, which allows it to slide along the connection member 3, oraugmentation material 7 may be solid, and connection member 3 can bethreaded through augmentation material by means such as needle or otherpuncturing device. Connection member 3 is affixed at one end to anchor 1and terminated at its other end by a support member 2′, one embodimentof which is shown in the figure in a cap-like configuration. Supportmember 2′ can be affixed to connection member 3 in a variety of ways,including, but not limited to, swaging support member 2′ to connectionmember 3. In a preferred embodiment, support member 2′ is in a capconfiguration and has a dimension (diameter or length and width) largerthan the optional passageway 9, which serves to prevent augmentationmaterial 7 from displacing posteriorly with respect to anchor 1. Theright half of the intervertebral disc of FIG. 7A (axial view) and FIG.7B (sagittal view) show augmentation material 7 that has been implantedinto the disc space 55 along connection member 3 where it supports thevertebral bodies 50 and 50′. FIG. 7A shows an embodiment in whichsupport member 2′ is affixed to connection member 3 and serves only toprevent augmentation material 7 from moving off connection member 3. Theaugmentation device is free to move within the disc space. FIG. 7B showsan alternate embodiment in which support member 2′ is embedded in a sitein the functional spine unit, such as a herniated segment or posteriorannulus fibrosis, to further restrict the movement of augmentationmaterial 7 or spacer material within the disc space.

Augmentation or spacer material can be made of any biocompatible,preferably flexible, material. Such a flexible material is preferablyfibrous, like cellulose or bovine or autologous collagen. Theaugmentation material can be plug or disc shaped. It can further becube-like, ellipsoid, spheroid or any other suitable shape. Theaugmentation material can be secured within the intervertebral space bya variety of methods, such as but not limited to, a suture loop attachedto, around, or through the material, which is then passed to the anchorand support member.

FIGS. 8, 9A, 9B and 10A and 10B depict further embodiments of the discherniation constraining device 13B in use for augmenting soft tissue,particularly tissue within the intervertebral space. In the embodimentsshown in FIGS. 8 and 9A, device 13B is secured within the intervertebraldisc space providing additional support for NP 20. Anchor 1 is securelyaffixed in a portion of the FSU, (anterior AF 10 in these figures).Connection member 3 terminates at support member 2, preventingaugmentation material 7 from migrating generally posteriorly withrespect to anchor 1. Support member 2 is depicted in these figures asestablished in various locations, such as the posterior AF 10′ in FIG.8, but support member 2 may be anchored in any suitable location withinthe FSU, as described previously. Support member 2 may be used to closea defect in the posterior AF. It may also be used to displace aherniated segment to within the pre-herniated borders of the disc byapplying tension between anchoring means 1 and 2 along connection member3.

FIG. 9A depicts anchor 1, connection member 3, spacer material 7 andsupport member 2′ (shown in the “cap”-type configuration) inserted as asingle construct and anchored to a site within the disc space, such asthe inferior or superior vertebral bodies. This configuration simplifiesinsertion of the embodiments depicted in FIGS. 7 and 8 by reducing thenumber of steps to achieve implantation. Connection member 3 ispreferably relatively stiff in tension, but flexible against all otherloads. Support member 2′ is depicted as a bar element that is largerthan passageway 9 in at least one plane.

FIG. 9B depicts a variation on the embodiment depicted in FIG. 9A. FIG.9B shows substantially one-piece disc augmentation device 13C, securedin the intervertebral disc space. Device 13C has anchor 1, connectionmember 3 and augmentation material 7. Augmentation material 7 and anchor1 could be pre-assembled prior to insertion into the disc space 55 as asingle construct. Alternatively, augmentation material 7 could beinserted first into the disc space and then anchored to a portion of theFSU by anchor 1.

FIGS. 10A and 10B show yet another embodiment of the disclosedinvention, 13D. In FIG. 10A, two connection members 3 and 3′ areattached to anchor 1. Two plugs of augmentation material 7 and 7′ areinserted into the disc space along connection members 3 and 3′.Connection members 3 and 3′ are then bound together (e.g., knottedtogether, fused, or the like). This forms loop 3″ that serves to preventaugmentation materials 7 and 7′ from displacing posteriorly. FIG. 10Bshows the position of the augmentation material 7 after it is secured bythe loop 3″ and anchor 1. Various combinations of augmentation material,connecting members and anchors can be used in this embodiment, such asusing a single plug of augmentation material, or two connection membersleading from anchor 1 with each of the connection members being bound toat least one other connection member. It could further be accomplishedwith more than one anchor with at least one connection member leadingfrom each anchor, and each of the connection members being bound to atleast one other connection member.

Any of the devices described herein can be used for closing defects inthe AF whether created surgically or during the herniation event. Suchmethods may also involve the addition of biocompatible material toeither the AF or NP. This material could include sequestered or extrudedsegments of the NP found outside the pre-hemiated borders of the disc.

FIGS. 11-15 illustrate devices used in and methods for closing a defectin an annulus fibrosis. One method involves the insertion of a barrieror barrier means 12 into the disc 15. This procedure can accompanysurgical discectomy. It can also be done without the removal of anyportion of the disc 15 and further in combination with the insertion ofan augmentation material or device into the disc 15.

The method consists of inserting the barrier 12 into the interior of thedisc 15 and positioning it proximate to the interior aspect of theannular defect 16. The barrier material is preferably considerablylarger in area than the size of the defect 16, such that at least someportion of the barrier means 12 abuts healthier annulus fibrosis 10. Thedevice acts to seal the annular defect 16, recreating the closedisobaric environment of a healthy disc nucleus 20. This closure can beachieved simply by an over-sizing of the implant relative to the defect16. It can also be achieved by affixing the barrier means 12 to tissueswithin the functional spinal unit. In a preferred aspect of the presentinvention, the barrier 12 is affixed to the annulus surrounding theannular defect 16. This can be achieved with sutures, staples, glues orother suitable fixation means or fixation device 14. The barrier means12 can also be larger in area than the defect 16 and be affixed to atissue or structure opposite the defect 16, i.e. anterior tissue in thecase of a posterior defect.

The barrier means 12 is preferably flexible in nature. It can beconstructed of a woven material such as Dacron™ or Nylon™, a syntheticpolyamide or polyester, a polyethylene, and can further be an expandedmaterial, such as expanded polytetrafluoroethylene (e-PTFE), forexample. The barrier means 12 can also be a biologic material such ascross-linked collagen or cellulous.

The barrier means 12 can be a single piece of material. It can have anexpandable means or component that allows it to be expanded from acompressed state after insertion into the interior of the disc 15. Thisexpandable means can be active, such as a balloon, or passive, such as ahydrophilic material. The expandable means can also be a self-expandingelastically deforming material, for example.

FIGS. 11 and 12 illustrate a barrier 12 mounted within an annulus 10 andcovering an annular defect 16. The barrier 12 can be secured to theannulus 10 with a fixation mechanism or fixation means 14. The fixationmeans 14 can include a plurality of suture loops placed through thebarrier 12 and the annulus 10. Such fixation can prevent motion orslipping of the barrier 12 away from the annular defect 16.

The barrier means 12 can also be anchored to the disc 15 in multiplelocations. In one preferred embodiment, shown in FIGS. 13 and 14, thebarrier means 12 can be affixed to the annulus tissue 10 in orsurrounding the defect and further affixed to a secondary fixation siteopposite the defect, e.g. the anterior annulus 10 in a posteriorherniation, or the inferior 50′ or superior 50 vertebral body. Forexample, fixation means 14 can be used to attach the barrier 12 to theannulus 10 near the defect 16, while an anchoring mechanism 18 cansecure the barrier 12 to a secondary fixation site. A connector 22 canattach the barrier 12 to the anchor 18. Tension can be applied betweenthe primary and secondary fixation sites through a connector 22 so as tomove the annular defect 16 toward the secondary fixation site. This maybe particularly beneficial in closing defects 16 that result inposterior herniations. By using this technique, the herniation can bemoved and supported away from any posterior neural structures whilefurther closing any defect in the annulus 10.

The barrier means 12 can further be integral to a fixation means suchthat the barrier means affixes itself to tissues within the functionalspinal unit.

Any of the methods described above can be augmented by the use of asecond barrier or a second barrier means 24 placed proximate to theouter aspect of the defect 16 as shown in FIG. 15. The second barrier 24can further be affixed to the inner barrier means 12 by the use of afixation means 14 such as suture material.

FIGS. 16A and 16B depict intervertebral disc 15 comprising nucleuspulposus 20 and annulus fibrosis 10. Nucleus pulposus 20 forms a firstanatomic region and extra-discal space 500 (any space exterior to thedisc) forms a second anatomic region wherein these regions are separatedby annulus fibrosis 10.

FIG. 16A is an axial (transverse) view of the intervertebral disc. Aposterior lateral defect 16 in annulus fibrosis 10 has allowed a segment30 of nucleus pulposus 20 to herniate into an extra discal space 500.Interior aspect 32 and exterior aspect 34 are shown, as are the right70′ and left 70 transverse processes and posterior process 80.

FIG. 16B is a sagittal section along the midline intervertebral disc.Superior pedicle 90 and inferior pedicle 90′ extend posteriorly fromsuperior vertebral body 95 and inferior vertebral body 95′ respectively.

To prevent further herniation of the nucleus 20 and to repair anypresent herniation, in a preferred embodiment, a barrier or barriermeans 12 can be placed into a space between the annulus 10 and thenucleus 20 proximate to the inner aspect 32 of defect 16, as depicted inFIGS. 17 and 18. The space can be created by blunt dissection.Dissection can be achieved with a separate dissection instrument, withthe barrier means 12 itself, or a combined dissection/barrier deliverytool 100. This space is preferably no larger than the barrier means suchthat the barrier means 12 can be in contact with both annulus 10 andnucleus 20. This allows the barrier means 12 to transfer load from thenucleus 20 to the annulus 10 when the disc is pressurized duringactivity.

In position, the barrier means 12 preferably spans the defect 16 andextends along the interior aspect 36 of the annulus 10 until it contactshealthy tissues on all sides of the defect 16. Depending on the extentof the defect 16, the contacted tissues can include the annulus 10,cartilage overlying the vertebral endplates, and/or the endplatesthemselves.

In the preferred embodiment, the barrier means 12 consists of twocomponents—a sealing means or sealing component 51 and an enlargingmeans or enlarging component 53, shown in FIGS. 21A and 21B.

The sealing means 51 forms the periphery of the barrier 12 and has aninterior cavity 17. There is at least one opening 8 leading into cavity17 from the exterior of the sealing means 51. Sealing means 51 ispreferably compressible or collapsible to a dimension that can readilybe inserted into the disc 15 through a relatively small hole. This holecan be the defect 16 itself or a site remote from the defect 16. Thesealing means 51 is constructed from a material and is formed in such amanner as to resist the passage of fluids and other materials aroundsealing means 51 and through the defect 16. The sealing means 51 can beconstructed from one or any number of a variety of materials including,but not limited to PTFE, e-PTFE, Nylon™, Marlex™, high-densitypolyethylene, and/or collagen. The thickness of the sealing componenthas been found to be optimal between 0.001 inches (0.127 mm) and 0.063inches (1.600 mm).

The enlarging means 53 can be sized to fit within cavity 17 of sealingmeans 51. It is preferably a single object of a dimension that can beinserted through the same defect 16 through which the sealing means 51was passed. The enlarging means 53 can expand the sealing means 51 to anexpanded state as it is passed into cavity 17. One purpose of enlargingmeans 53 is to expand sealing means 51 to a size greater than that ofthe defect 16 such that the assembled barrier 12 prevents passage ofmaterial through the defect 16. The enlarger 53 can further impartstiffness to the barrier 12 such that the barrier 12 resists thepressures within nucleus pulposus 20 and expulsion through the defect16. The enlarging means 53 can be constructed from one or any number ofmaterials including, but not limited to, silicon rubber, variousplastics, stainless steel, nickel titanium alloys, or other metals.These materials may form a solid object, a hollow object, coiled springsor other suitable forms capable of filling cavity 17 within sealingmeans 51.

The sealing means 51, enlarging means 53, or the barrier means 12constructs can further be affixed to tissues either surrounding thedefect 16 or remote from the defect 16. In the preferred embodiment, noaspect of a fixation means or fixation device or the barrier means 12nor its components extend posterior to the disc 15 or into theextradiscal region 500, avoiding the risk of contacting and irritatingthe sensitive nerve tissues posterior to the disc 15.

In a preferred embodiment, the sealing means 51 is inserted into thedisc 15 proximate the interior aspect 36 of the defect. The sealingmeans 51 is then affixed to the tissues surrounding the defect using asuitable fixation means, such as suture or a soft-tissue anchor. Thefixation procedure is preferably performed from the interior of thesealing means cavity 17 as depicted in FIGS. 19 and 20. A fixationdelivery instrument 110 is delivered into cavity 17 through opening 8 inthe sealing means 51. Fixation devices 14 can then be deployed through awall of the sealing means 53 into surrounding tissues. Once the fixationmeans 14 have been passed into surrounding tissue, the fixation deliveryinstrument 110 can be removed from the disc 15. This method eliminatesthe need for a separate entryway into the disc 15 for delivery offixation means 14. It further minimizes the risk of material leakingthrough sealing means 51 proximate to the fixation means 14. One or morefixation means 14 can be delivered into one or any number of surroundingtissues including the superior 95 and inferior 95′ vertebral bodies.Following fixation of the sealing means 51, the enlarging means 53 canbe inserted into cavity 17 of the sealing means 51 to further expand thebarrier means 12 construct as well as increase its stiffness, asdepicted in FIGS. 21A and 21B. The opening 8 into the sealing means 51can then be closed by a suture or other means, although this is not arequirement of the present invention. In certain cases, insertion of aseparate enlarging means may not be necessary if adequate fixation ofthe sealing means 51 is achieved.

Another method of securing the barrier 12 to tissues is to affix theenlarging means 53 to tissues either surrounding or remote from thedefect 16. The enlarging means 53 can have an integral fixation region 4that facilitates securing it to tissues as depicted in FIGS. 22A, 22B,32A and 43B. This fixation region 4 can extend exterior to sealing means51 either through opening 8 or through a separate opening. Fixationregion 4 can have a hole through which a fixation means or fixationdevice 14 can be passed. In a preferred embodiment, the barrier 12 isaffixed to at least one of the surrounding vertebral bodies (95 and 95′)proximate to the defect using a bone anchor 14′. The bone anchor 14′ canbe deployed into the vertebral bodies 50, 50′ at some angle between0.degree and 180.degree. relative to a bone anchor deployment tool. Asshown the bone anchor 14′ is mounted at 90.degree. relative to the boneanchor deployment tool. Alternatively, the enlarging means 53 itself canhave an integral fixation device 14 located at a site or sites along itslength.

Another method of securing the barrier means 12 is to insert the barriermeans 12 through the defect 16 or another opening into the disc 15,position it proximate to the interior aspect 36 of the defect 16, andpass at least one fixation means 14 through the annulus 10 and into thebarrier 12. In a preferred embodiment of this method, the fixation means14 can be darts 15 and are first passed partially into annulus 10 withina fixation device 120, such as a hollow needle. As depicted in FIGS. 23Aand 23B, fixation means 25 can be advanced into the barrier means 12 andfixation device 120 removed. Fixation means 25 preferably have two ends,each with a means to prevent movement of that end of the fixationdevice. Using this method, the fixation means can be lodged in both thebarrier 12 and annulus fibrosis 10 without any aspect of fixation means25 exterior to the disc in the extradiscal region 500.

In another aspect of the present invention, the barrier (or “patch”) 12can be placed between two neighboring layers 33,37 (lamellae) of theannulus 10 on either or both sides of the defect 16 as depicted in FIGS.24A and 24B. FIG. 24A shows an axial view while 24B shows a sagittalcross section. Such positioning spans the defect 16. The barrier means12 can be secured using the methods outlined.

A dissecting tool can be used to form an opening extendingcircumferentially 31 within the annulus fibrosis such that the barriercan be inserted into the opening. Alternatively, the barrier itself canhave a dissecting edge such that it can be driven at least partiallyinto the sidewalls of defect or opening 16 in the annulus. This processcan make use of the naturally layered structure in the annulus in whichadjacent layers 33, 37 are defined by a circumferentially extendingboundary 35 between the layers.

Another embodiment of the barrier 12 is a patch having a length,oriented along the circumference of the disc, which is substantiallygreater than its height, which is oriented along the distance separatingthe surrounding vertebral bodies. A barrier 12 having a length greaterthan its height is illustrated in FIG. 25. The barrier 12 can bepositioned across the defect 16 as well as the entirety of the posterioraspect of the annulus fibrosis 10. Such dimensions of the barrier 12 canhelp to prevent the barrier 12 from slipping after insertion and can aidin distributing the pressure of the nucleus 20 evenly along theposterior aspect of the annulus 10.

The barrier 12 can be used in conjunction with an augmentation device 11inserted within the annulus 10. The augmentation device 11 can includeseparate augmentation devices 42 as shown in FIG. 26. The augmentationdevice 11 can also be a single augmentation device 44 and can form partof the barrier 12 as barrier region 300, coiled within the annulusfibrosis 10, as shown in FIG. 27. Either the barrier 12 or barrierregion 300 can be secured to the tissues surrounding the defect 16 byfixation devices or darts 25, or be left unconstrained.

In another embodiment of the present invention, the barrier or patch 12may be used as part of a method to augment the intervertebral disc. Inone aspect of this method, augmentation material or devices are insertedinto the disc through a defect (either naturally occurring or surgicallygenerated). Many suitable augmentation materials and devices arediscussed above and in the prior art. As depicted in FIG. 26, thebarrier means is then inserted to aid in closing the defect and/or toaid in transferring load from the augmentation materials/devices tohealthy tissues surrounding the defect. In another aspect of thismethod, the barrier means is an integral component to an augmentationdevice. As shown in FIGS. 27, 28A and 28B, the augmentation portion maycomprise a length of elastic material that can be inserted linearlythrough a defect in the annulus. A region 300 of the length forms thebarrier means of the present invention and can be positioned proximateto the interior aspect of the defect once the nuclear space isadequately filled. Barrier region 300 may then be affixed to surroundingtissues such as the AF and/or the neighboring vertebral bodies using anyof the methods and devices described above.

FIGS. 28A and 28B illustrate axial and sagittal sections, respectively,of an alternate configuration of an augmentation device 38. In thisembodiment, barrier region 300 extends across the defect 16 and hasfixation region 4 facilitating fixation of the device 13 to superiorvertebral body 50 with anchor 14′.

FIGS. 29A-D illustrate the deployment of a barrier 12 from an entry site800 remote from the defect in the annulus fibrosis 10. FIG. 29A showsinsertion instrument 130 with a distal end positioned within the discspace occupied by nucleus pulposus 20. FIG. 29B depicts deliverycatheter 140 exiting the distal end of insertion instrument 130 withbarrier 12 on its distal end. Barrier 12 is positioned across theinterior aspect of the defect 16. FIG. 29C depicts the use of anexpandable barrier 12′ wherein delivery catheter 140 is used to expandthe barrier 12′ with balloon 150 on its distal end. Balloon 150 mayexploit heat to further adhere barrier 12′ to surrounding tissue. FIG.29D depicts removal of balloon 150 and delivery catheter 140 from thedisc space leaving expanded barrier means 12′ positioned across defect16.

Another method of securing the barrier means 12 is to adhere it tosurrounding tissues through the application of heat. In this embodiment,the barrier means 12 includes a sealing means 51 comprised of athermally adherent material that adheres to surrounding tissues upon theapplication of heat. The thermally adherent material can includethermoplastic, collagen, or a similar material. The sealing means 51 canfurther comprise a separate structural material that adds strength tothe thermally adherent material, such as a woven Nylon™ or Marlex™. Thisthermally adherent sealing means preferably has an interior cavity 17and at least one opening 8 leading from the exterior of the barriermeans into cavity 17. A thermal device can be attached to the insertioninstrument shown in FIGS. 29C and 29D. The insertion instrument 130having a thermal device can be inserted into cavity 17 and used to heatsealing means 51 and surrounding tissues. This device can be a simplethermal element, such as a resistive heating coil, rod or wire. It canfurther be a number of electrodes capable of heating the barrier meansand surrounding tissue through the application of radio frequency (RF)energy. The thermal device can further be a balloon 150, 150′, as shownin FIG. 47, capable of both heating and expanding the barrier means.Balloon 150, 150′ can either be inflated with a heated fluid or haveelectrodes located about its surface to heat the barrier means with RFenergy. Balloon 150, 150′ is deflated and removed after heating thesealing means. These thermal methods and devices achieve the goal ofadhering the sealing means to the AF and NP and potentially othersurrounding tissues. The application of heat can further aid theprocedure by killing small nerves within the AF, by causing the defectto shrink, or by causing cross-linking and/or shrinking of surroundingtissues. An expander or enlarging means 53 can also be an integralcomponent of barrier 12 inserted within sealing means 51. After theapplication of heat, a separate enlarging means 53 can be inserted intothe interior cavity of the barrier means to either enlarge the barrier12 or add stiffness to its structure. Such an enlarging means ispreferably similar in make-up and design to those described above. Useof an enlarging means may not be necessary in some cases and is not arequired component of this method.

The barrier means 12 shown in FIG. 25 preferably has a primary curvatureor gentle curve along the length of the patch or barrier 12 that allowsit to conform to the inner circumference of the AF 10. This curvaturemay have a single radius R as shown in FIGS. 44A and 44B or may havemultiple curvatures. The curvature can be fabricated into the barrier 12and/or any of its components. For example, the sealing means can be madewithout an inherent curvature while the enlarging means can have aprimary curvature along its length. Once the enlarging means is placedwithin the sealing means the overall barrier means assembly takes on theprimary curvature of the enlarging means. This modularity allowsenlarging means with specific curvatures to be fabricated for defectsoccurring in various regions of the annulus fibrosis.

The cross section of the barrier 12 can be any of a number of shapes.Each embodiment exploits a sealing means 51 and an enlarging means 53that may further add stiffness to the overall barrier construct. FIGS.30A and 30B show an elongated cylindrical embodiment with enlargingmeans 53 located about the long axis of the device. FIGS. 31A and 31Bdepict a barrier means comprising an enlarging means 53 with a centralcavity 49. FIGS. 32A and 32B depict a barrier means comprising anon-axisymmetric sealing means 51. In use, the longer section of sealingmeans 51 as seen on the left side of this figure would extend betweenopposing vertebra 50 and 50′. FIGS. 33A and 33B depict a barrier meanscomprising a non-axisymmetric sealing means 51 and enlarger 53. Theconcave portion of the barrier means preferably faces nucleus pulposus20 while the convex surface faces the defect 16 and the inner aspect ofthe annulus fibrosis 10. This embodiment exploits pressure within thedisc to compress sealing means 51 against neighboring vertebral bodies50 and 50′ to aid in sealing. The ‘C’ shape as shown in FIG. 33A is thepreferred shape of the barrier wherein the convex portion of the patchrests against the interior aspect of the AF while the concave portionfaces the NP. To improve the sealing ability of such a patch, the upperand lower portions of this ‘C’ shaped barrier means are positionedagainst the vertebral endplates or overlying cartilage. As the pressurewithin the nucleus increases, these portions of the patch arepressurized toward the endplates with an equivalent pressure, preventingthe passage of materials around the barrier means. Dissecting a matchingcavity prior to or during patch placement can facilitate use of such a‘C’ shaped patch.

FIGS. 34 through 41 depict various enlarging or expansion devices 53that can be employed to aid in expanding a sealing element 51 within theintervertebral disc 15. Each embodiment can be covered by, coated with,or cover the sealing element 51. The sealing means 51 can further bewoven through the expansion means 53. The sealing element 51 or membranecan be a sealer which can prevent flow of a material from within theannulus fibrosis of the intervertebral disc through a defect in theannulus fibrosis. The material within the annulus can include nucleuspulposus or a prosthetic augmentation device, such as a hydrogel.

FIGS. 34 through 38 depict alternative patterns to that illustrated inFIG. 33A. FIG. 33A shows the expansion devices 53 within the sealingmeans 51. The sealing means can alternatively be secured to one oranother face (concave or convex) of the expansion means 53. This canhave advantages in reducing the overall volume of the barrier means 12,simplifying insertion through a narrow cannula. It can also allow thebarrier means 12 to induce ingrowth of tissue on one face and not theother. The sealing means 51 can be formed from a material that resistsingrowth such as expanded polytetrafluoroethylene (e-PTFE). Theexpansion means 53 can be constructed of a metal or polymer thatencourages ingrowth. If the e-PTFE sealing means 51 is secured to theconcave face of the expansion means 53, tissue can grow into theexpansion means 53 from outside of the disc 15, helping to secure thebarrier means 12 in place and seal against egress of materials fromwithin the disc 15. The expansion means 53 shown in FIG. 33A can beinserted into the sealing means 51 once the sealing means 51 is withinthe disc 15. Alternatively, the expansion means 53 and sealing means 51can be integral components of the barrier means 12 that can be insertedas a unit into the disc.

The patterns shown in FIGS. 34 through 38 can preferably be formed froma relatively thin sheet of material. The material may be a polymer,metal, or gel, however, the super elastic properties of nickel titaniumalloy (NITINOL) makes this metal particularly advantageous in thisapplication. Sheet thickness can generally be in a range of 0.1 mm to0.6 mm and for certain embodiments has been found to be optimal ifbetween 0.003″ to 0.015″ (0.0762 mm to 0.381 mm), for the thickness toprovide adequate expansion force to maintain contact between the sealingmeans 51 and surrounding vertebral endplates. The pattern may be WireElectro-Discharge Machined, cut by laser, chemically etched, or formedby other suitable means.

FIG. 34A shows an embodiment of a non-axisymmetric expander 153 having asuperior edge 166 and an inferior edge 168. The expander 153 can form aframe of barrier 12. This embodiment comprises dissecting surfaces orends 160, radial elements or fingers 162 and a central strut 164. Thecircular shape of the dissecting ends 160 aids in dissecting through thenucleus pulposus 20 and/or along or between an inner surface of theannulus fibrosis 10. The distance between the left-most and right-mostpoints on the dissecting ends is the expansion means length 170. Thislength 170 preferably lies along the inner perimeter of the posteriorannulus following implantation. The expander length 170 can be as shortas 3 mm and as long as the entire interior perimeter of the annulusfibrosis. The superior-inferior height of these dissecting ends 160 ispreferably similar to or larger than the posterior disc height.

This embodiment employs a multitude of fingers 162 to aid in holding aflexible sealer or membrane against the superior and inferior vertebralendplates. The distance between the superior-most point of the superiorfinger and the inferior-most point on the inferior finger is theexpansion means height 172. This height 172 is preferably greater thanthe disc height at the inner surface of the posterior annulus. Thegreater height 172 of the expander 153 allows the fingers 162 to deflectalong the superior and inferior vertebral endplates, enhancing the sealof the barrier means 12 against egress of material from within the disc15.

The spacing between the fingers 162 along the expander length 170 can betailored to provide a desired stiffness of the expansion means 153.Greater spacing between any two neighboring fingers 162 can further beemployed to insure that the fingers 170 do not touch if the expansionmeans 153 is required to take a bend along its length. The central strut164 can connect the fingers and dissecting ends and preferably liesalong the inner surface of the annulus 10 when seated within the disc15. Various embodiments may employ struts 164 of greater or lesserheights and thicknesses to vary the stiffness of the overall expansionmeans 153 along its length 170 and height 172.

FIG. 35 depicts an alternative embodiment to the expander 153 of FIG.34. Openings or slots 174 can be included along the central strut 164.These slots 174 promote bending of the expander 153 and fingers 162along a central line 176 connecting the centers of the dissecting ends160. Such central flexibility has been found to aid against superior orinferior migration of the barrier means or barrier 12 when the barrier12 has not been secured to surrounding tissues.

FIGS. 34B and 34C depict different perspective views of a preferredembodiment of the expander/frame 153 within an intervertebral disc 15.Expander 53 is in its expanded condition and lies along and/or withinthe posterior wall 21 and extends around the lateral walls 23 of theannulus fibrosis 10. The superior 166 and inferior 168 facing fingers162 of expander 153 extend along the vertebral endplates (not shown)and/or the cartilage overlying the endplates. The frame 153 can take ona 3-D concave shape in this preferred position with the concavitygenerally directed toward the interior of the intervertebral disc andspecifically a region occupied by the nucleus pulposus 20.

The bending stiffness of expander 153 can resist migration of theimplant from this preferred position within the disc 15. The principlebehind this stiffness-based stability is to place the regions ofexpander 153 with the greatest flexibility in the regions of the disc153 with the greatest mobility or curvature. These flexible regions ofexpander 153 are surrounded by significantly stiffer regions. Hence, inorder for the implant to migrate, a relatively stiff region of theexpander must move into a relatively curved or mobile region of thedisc.

For example, in order for expander 153 of FIG. 34B to move around theinner circumference of annulus fibrosis 10. (i.e. from the posteriorwall 21 onto the lateral 23 and/or anterior 27 wall), the stiff centralregion of expander 153 spanning the posterior wall 21 would have to bendaround the acute curves of the posterior lateral corners of annulus 10.The stiffer this section of expander 153 is, the higher the forcesnecessary to force it around these comers and the less likely it is tomigrate in this direction. This principle was also used in thisembodiment to resist migration of fingers 162 away from the vertebralendplates: The slots 174 cut along the length of expander 153 create acentral flexibility that encourages expander 153 to bend along an axisrunning through these slots as the posterior disc height increases anddecreased during flexion and extension. In order for the fingers 162 tomigrate away from the endplate, this central flexible region must moveaway from the posterior annulus 21 and toward an endplate. This motionis resisted by the greater stiffness of expander 153 in the areasdirectly inferior and superior to this central flexible region.

The expander 153 is preferably covered by a membrane that acts tofurther restrict the movement of materials through the frame and towardthe outer periphery of the annulus fibrosis.

FIG. 36 depicts an embodiment of the expander 153 of FIG. 33A with anenlarged central strut 164 and a plurality of slots 174. This centralstrut 164 can have a uniform stiffness against superior-inferior 166 and168 bending as shown in this embodiment. The strut 164 can alternativelyhave a varying stiffness along its height 178 to either promote orresist bending at a given location along the inner surface of theannulus 10.

FIGS. 37A-C depict a further embodiment of the frame or expander 153.This embodiment employs a central lattice 180 consisting of multiple,fine interconnected struts 182. Such a lattice 180 can provide astructure that minimizes bulging of the sealing means 51 underintradiscal pressures. The orientation and location of these struts 182have been designed to give the barrier 12 a bend-axis along the centralarea of the expander height 172. The struts 182 support inferior 168 andsuperior 166 fingers 162 similar to previously described embodiments.However, these fingers 162 can have varying dimensions and stiffnessalong the length of the barrier 12. Such fingers 162 can be useful forhelping the sealer 51 conform to uneven endplate geometries. FIG. 37Billustrates the curved cross section 184 of the expander 153 of FIG.37A. This curve 184 can be an arc segment of a circle as shown.Alternatively, the cross section can be an ellipsoid segment or have amultitude of arc segments of different radii and centers. FIG. 37C is aperspective view showing the three dimensional shape of the expander 153of FIGS. 37A and 37B.

The embodiment of the frame 153 as shown in FIGS. 37A C, can also beemployed without the use of a covering membrane. The nucleus pulposus ofmany patients with low back pain or disc herniation can degenerate to astate in which the material properties of the nucleus cause it to behavemuch more like a solid than a gel. As humans age, the water content ofthe nucleus declines from roughly 88% to less than 75%. As this occurs,there is an increase in the cross linking of collagen within the discresulting in a greater solidity of the nucleus. When the pore size orthe largest open area of any given gap in the lattice depicted in FIGS.37A, 37B, and 37C is between 0.05 mm.sup.2 (7.75.times.10.sup.-5in.sup.2) and 0.75 mm.sup.2 (1.16.times.10.sup.-3 in.sup.2), the nucleuspulposus is unable to extrude through the lattice at pressures generatedwithin the disc (between 250 KPa and 1.8 MPa). The preferred pore sizehas been found to be approximately 0.15 mm.sup.2 (2.33.times.10.sup.−4in.sup.2). This pore size can be used with any of the disclosedembodiments of the expander or any other expander that falls within thescope of the present invention to prevent movement of nucleus toward theouter periphery of the disc without the need for an additional membrane.The membrane thickness is preferably in a range of 0.025 mm to 2.5 mm.

FIG. 38 depicts an expander 153 similar to that of FIG. 37A withoutfingers. The expander 153 includes a central lattice 180 consisting ofmultiple struts 182.

FIGS. 39 through 41 depict another embodiment of the expander 153 of thepresent invention. These tubular expanders can be used in the barrier 12embodiment depicted in FIG. 31A. The sealer 51 can cover the expander153 as shown in FIG. 31A. Alternatively, the sealer 51 can cover theinterior surface of the expander or an arc segment of the tube along itslength on either the interior or exterior surface.

FIG. 39 depicts an embodiment of a tubular expander 154. The superior166 and inferior surfaces 168 of the tubular expander 154 can deployagainst the superior and inferior vertebral endplates, respectively. Thedistance 186 between the superior 166 and inferior 168 surfaces of theexpander 154 are preferably equal to or greater than the posterior discheight at the inner surface of the annulus 10. This embodiment has anannulus face 188 and nucleus face 190 as shown in FIGS. 39B, 39C and39D. The annulus face 188 can be covered by the sealer 51 from thesuperior 166 to inferior 168 surface of the expander 154. This face 188lies against the inner surface of the annulus 10 in its deployedposition and can prevent egress of materials from within the disc 15.The primary purpose of the nucleus face 190 is to prevent migration ofthe expander 154 within the disc 15. The struts 192 that form thenucleus face 190 can project anteriorly into the nucleus 20 when thebarrier 12 is positioned across the posterior wall of the annulus 10.This anterior projection can resist rotation of the tubular expansionmeans 154 about its long axis. By interacting with the nucleus 20, thestruts 192 can further prevent migration around the circumference of thedisc 15.

The struts 192 can be spaced to provide nuclear gaps 194. These gaps 194can encourage the flow of nucleus pulposus 20 into the interior of theexpander 154. This flow can insure full expansion of the barrier 12within the disc 15 during deployment.

The embodiments of FIGS. 39, 40 and 41 vary by their cross-sectionalshape. FIG. 39 has a circular cross section 196 as seen in FIG. 39C. Ifthe superior-inferior height 186 of the expander 154 is greater thanthat of the disc 15, this circular cross section 196 can deform into anoval when deployed, as the endplates of the vertebrae compress theexpander 154. The embodiment of the expander 154 shown in FIG. 40 ispreformed into an oval shape 198 shown in FIG. 40C. Compression by theendplates can exaggerate the unstrained oval 198. This oval 198 canprovide greater stability against rotation about a long axis of theexpander 154. The embodiment of FIGS. 41B, 41C and 41D depict an‘egg-shaped’ cross section 202, as shown in FIG. 41C, that can allowcongruity between the curvature of the expander 154 and the inner wallof posterior annulus 10. Any of a variety of alternate cross sectionalshapes can be employed to obtain a desired fit or expansion forcewithout deviating from the spirit of the present invention.

FIGS. 40E, 40F, and 40I depict the expander 154 of FIGS. 40A D having asealing means 51 covering the exterior surface of the annulus face 188.This sealing means 51 can be held against the endplates and the innersurface of the posterior annulus by the expander 154 in its deployedstate.

FIGS. 40G and 40H depict the expander 154 of FIG. 40B with a sealer 51covering the interior surface of the annulus face 188. This position ofthe sealer 51 can allow the expander 154 to contact both the vertebralendplates and inner surface of the posterior annulus. This can promoteingrowth of tissue into the expander 154 from outside the disc 15.Combinations of sealer 51 that cover all or part of the expander 154 canalso be employed without deviating from the scope of the presentinvention. The expander 154 can also have a small pore size therebyallowing retention of a material such as a nucleus pulposus, forexample, without the need for a sealer as a covering.

FIGS. 42A-D depict cross sections of a preferred embodiment of sealingmeans 51 and enlarging means 53. Sealing means 51 has internal cavity 17and opening 8 leading from its outer surface into internal cavity 17.Enlarger 53 can be inserted through opening 8 and into internal cavity17.

FIGS. 43A and 43B depict an alternative configuration of enlarger 53.Fixation region 4 extends through opening 8 in sealing means 51.Fixation region 4 has a through-hole that can facilitate fixation ofenlarger 53 to tissues surrounding defect 16.

FIGS. 44A and 44B depict an alternative shape of the barrier. In thisembodiment, sealing means 51, enlarger 53, or both have a curvature withradius R. This curvature can be used in any embodiment of the presentinvention and may aid in conforming to the curved inner circumference ofannulus fibrosis 10.

FIG. 45 is a section of a device used to affix sealing means 51 totissues surrounding a defect. In this figure, sealing means 51 would bepositioned across interior aspect 50 of defect 16. The distal end ofdevice 110′ would be inserted through defect 16 and opening 8 into theinterior cavity 17. On the right side of this figure, fixation dart 25has been passed from device 110′, through a wall of sealing means 51 andinto tissues surrounding sealing means 51. On the right side of thefigure, fixation dart 25 is about to be passed through a wall of sealingmeans 51 by advancing pusher 111 relative to device 110′ in thedirection of the arrow.

FIG. 46 depicts the use of thermal device 200 to heat sealing means 51and adhere it to tissues surrounding a defect. In this figure, sealingmeans 51 would be positioned across the interior aspect 36 of a defect16. The distal end of thermal device 200 would be inserted through thedefect and opening 8 into interior cavity 17. In this embodiment,thermal device 200 employs at its distal end resistive heating element210 connected to a voltage source by wires 220. Covering 230 is anon-stick surface such as Teflon tubing that ensures the ability toremove device 200 from interior cavity 17. In this embodiment, device200 would be used to heat first one half, and then the other half ofsealing means 51.

FIG. 47 depicts an expandable thermal element, such as a balloon, thatcan be used to adhere sealing means 51 to tissues surrounding a defect.As in FIG. 18, the distal end of device 130 can be inserted through thedefect and opening 8 into interior cavity 17, with balloon 150′ on thedistal end device 130 in a collapsed state. Balloon 150′ is theninflated to expanded state 150, expanding sealing means 51. Expandedballoon 150 can heat sealing means 51 and surrounding tissues byinflating it with a heated fluid or by employing RF electrodes. In thisembodiment, device 130 can be used to expand and heat first one half,then the other half of sealing means 51.

FIG. 48 depicts an alternative embodiment to device 130. This deviceemploys an elongated, flexible balloon 150′ that can be inserted intoand completely fill internal cavity 17 of sealing means 51 prior toinflation to an expanded state 150. Using this embodiment, inflation andheating of sealing means 51 can be performed in one step.

FIGS. 49A through 49G illustrate a method of implanting an intradiscalimplant. An intradiscal implant system consists of an intradiscalimplant 400, a delivery device or cannula 402, an advancer 404 and atleast one control filament 406. The intradiscal implant 400 is loadedinto the delivery cannula 402 which has a proximal end 408 and a distalend 410. FIG. 49A illustrates the distal end 410 advanced into the disc15 through an annulotomy 416. This annulotomy 416 can be through anyportion of the annulus 10, but is preferably at a site proximate to adesired, final implant location. The implant 400 is then pushed into thedisc 15 through the distal end 410 of the cannula 402 in a directionthat is generally away from the desired, final implant location as shownin FIG. 49B. Once the implant 400 is completely outside of the deliverycannula 402 and within the disc 15, the implant 400 can be pulled intothe desired implant location by pulling on the control filament 406 asshown in FIG. 49C. The control filament 406 can be secured to theimplant 400 at any location on or within the implant 400, but ispreferably secured at least at a site 414 or sites on a distal portion412 of the implant 400, i.e. that portion that first exits the deliverycannula 402 when advanced into the disc 15. These site or sites 414 aregenerally furthest from the desired, final implant location once theimplant has been fully expelled from the interior of the deliverycannula 402.

Pulling on the control filament 406 causes the implant 400 to movetoward the annulotomy 416. The distal end 410 of the delivery cannula402 can be used to direct the proximal end 420 of the implant 400 (thatportion of the implant 400 that is last to be expelled from the deliverycannula 402) away from the annulotomy 416 and toward an inner aspect ofthe annulus 10 nearest the desired implant location. Alternately, theadvancer 404 can be used to position the proximal end of the implanttoward an inner aspect of the annulus 20 near the implant location, asshown in FIG. 49E. Further pulling on the control filament 406 causesthe proximal end 426 of the implant 400 to dissect along the inneraspect of the annulus 20 until the attachment site 414 or sites of theguide filament 406 to the implant 400 has been pulled to the inneraspect of the annulotomy 416, as shown in FIG. 49D. In this way, theimplant 400 will extend at least from the annulotomy 416 and along theinner aspect of the annulus 10 in the desired implant location,illustrated in FIG. 49F.

The implant 400 can be any of the following: nucleus replacement device,nucleus augmentation device, annulus augmentation device, annulusreplacement device, the barrier of the present invention or any of itscomponents, drug carrier device, carrier device seeded with livingcells, or a device that stimulates or supports fusion of the surroundingvertebra. The implant 400 can be a membrane which prevents the flow of amaterial from within the annulus fibrosis of an intervertebral discthrough a defect in the disc. The material within the annulus fibrosiscan be, for example, a nucleus pulposus or a prosthetic augmentationdevice, such as hydrogel. The membrane can be a sealer. The implant 400can be wholly or partially rigid or wholly or partially flexible. It canhave a solid portion or portions that contain a fluid material. It cancomprise a single or multitude of materials. These materials can includemetals, polymers, gels and can be in solid or woven form. The implant400 can either resist or promote tissue ingrowth, whether fibrous orbony.

The cannula 402 can be any tubular device capable of advancing theimplant 400 at least partially through the annulus 10. It can be made ofany suitable biocompatible material including various known metals andpolymers. It can be wholly or partially rigid or flexible. It can becircular, oval, polygonal, or irregular in cross section. It must havean opening at least at its distal end 410, but can have other openingsin various locations along its length.

The advancer 404 can be rigid or flexible, and have one of a variety ofcross sectional shapes either like or unlike the delivery cannula 402.It may be a solid or even a column of incompressible fluid, so long asit is stiff enough to advance the implant 400 into the disc 15. Theadvancer 404 can be contained entirely within the cannula 402 or canextend through a wall or end of the cannula to facilitate manipulation.

Advancement of the implant 400 can be assisted by various levers, gears,screws and other secondary assist devices to minimize the force requiredby the surgeon to advance the implant 400. These secondary devices canfurther give the user greater control over the rate and extent ofadvancement into the disc 15.

The guide filament 406 may be a string, rod, plate, or other elongateobject that can be secured to and move with the implant 400 as it isadvanced into the disc 15. It can be constructed from any of a varietyof metals or polymers or combination thereof and can be flexible orrigid along all or part of its length. It can be secured to a secondaryobject 418 or device at its end opposite that which is secured to theimplant 400. This secondary device 418 can include the advancer 404 orother object or device that assists the user in manipulating thefilament. The filament 406 can be releasably secured to the implant 400,as shown in FIG. 49G or permanently affixed. The filament 406 can belooped around or through the implant. Such a loop can either be cut orhave one end pulled until the other end of the loop releases the implant400. It may be bonded to the implant 400 using adhesive, welding, or asecondary securing means such as a screw, staple, dart, etc. Thefilament 406 can further be an elongate extension of the implantmaterial itself. If not removed following placement of the implant, thefilament 406 can be used to secure the implant 400 to surroundingtissues such as the neighboring annulus 10, vertebral endplates, orvertebral bodies either directly or through the use of a dart, screw,staple, or other suitable anchor.

Multiple guide filaments can be secured to the implant 400 at variouslocations. In one preferred embodiment, a first or distal 422 and asecond or proximal 424 guide filament are secured to an elongate implant400 at or near its distal 412 and proximal 420 ends at attachment sites426 and 428, respectively. These ends 412 and 420 correspond to thefirst and last portions of the implant 400, respectively, to be expelledfrom the delivery cannula 402 when advanced into the disc 15. Thisdouble guide filament system allows the implant 400 to be positioned inthe same manner described above in the single filament technique, andillustrated in FIGS. 50A C. However, following completion of this firsttechnique, the user may advance the proximal end 420 of the device 400across the annulotomy 416 by pulling on the second guide filament 424,shown in FIG. 50D. This allows the user to controllably cover theannulotomy 416. This has numerous advantages in various implantationprocedures. This step may reduce the risk of herniation of eithernucleus pulposus 20 or the implant itself. It may aid in sealing thedisc, as well as preserving disc pressure and the natural function ofthe disc. It may encourage ingrowth of fibrous tissue from outside thedisc into the implant. It may further allow the distal end of theimplant to rest against annulus further from the defect created by theannulotomy. Finally, this technique allows both ends of an elongateimplant to be secured to the disc or vertebral tissues.

Both the first 422 and second 424 guide filaments can be simultaneouslytensioned, as shown in FIG. 50E, to ensure proper positioning of theimplant 400 within the annulus 10. Once the implant 400 is placed acrossthe annulotomy, the first 422 and second 424 guide filaments can beremoved from the input 400, as shown in FIG. 50F. Additional controlfilaments and securing sites may further assist implantation and/orfixation of the intradiscal implants.

In another embodiment of the present invention, as illustrated in FIGS.51 A C, an implant guide 430 may be employed to aid directing theimplant 400 through the annulotomy 416, through the nucleus pulposus 10,and/or along the inner aspect of the annulus 10. This implant guide 430can aid in the procedure by dissecting through tissue, adding stiffnessto the implant construct, reducing trauma to the annulus or othertissues that can be caused by a stiff or abrasive implant, providing 3-Dcontrol of the implants orientation during implantation, expanding anexpandable implant, or temporarily imparting a shape to the implant thatis beneficial during implantation. The implant guide 430 can be affixedto either the advancer 404 or the implant 406 themselves. In a preferredembodiment shown in FIGS. 52A and 52B, the implant guide 430 is securedto the implant 400 by the first 424 and second 426 guide filaments ofthe first 426 and the second 428 attachment sites, respectively. Theguide filaments 424 and 426 may pass through or around the implant guide430. In this embodiment, the implant guide 430 may be a thin, flat sheetof biocompatible metal with holes passing through its surface proximateto the site or sites 426 and 428 at which the guide filaments 422 and424 are secured to the implant 400. These holes allow passage of thesecuring filament 422 and 424 through the implant guide 430. Such anelongated sheet may run along the implant 400 and extend beyond itsdistal end 412. The distal end of the implant guide 430 may be shaped tohelp dissect through the nucleus 10 and deflect off of the annulus 10 asthe implant 400 is advanced into the disc 15. When used with multipleguide filaments, such an implant guide 430 can be used to controlrotational stability of the implant 400. It may also be used to retractthe implant 400 from the disc 15 should this become necessary. Theimplant guide 430 may also extend beyond the proximal tip 420 of theimplant 400 to aid in dissecting across or through the annulus 10proximate to the desired implantation site.

The implant guide 430 is releasable from the implant 400 following orduring implantation. This release may be coordinated with the release ofthe guide filaments 422 and 424. The implant guide 430 may further beable to slide along the guide filaments 422 and 424 while thesefilaments are secured to the implant 400.

Various embodiments of the barrier 12 or implant 400 can be secured totissues within the intervertebral disc 15 or surrounding vertebrae. Itcan be advantageous to secure the barrier means 12 in a limited numberof sites while still insuring that larger surfaces of the barrier 12 orimplant juxtapose the tissue to which the barrier 12 is secured. This isparticularly advantageous in forming a sealing engagement withsurrounding tissues.

FIGS. 53-57 illustrate barriers having stiffening elements 300. Thebarrier 12 can incorporate stiffening elements 300 that run along alength of the implant required to be in sealing engagement. Thesestiffening elements 300 can be one of a variety of shapes including, butnot limited to, plates 302, rods 304, or coils. These elements arepreferably stiffer than the surrounding barrier 12 and can impart theirstiffness to the surrounding barrier. These stiffening elements 300 canbe located within an interior cavity formed by the barrier. They canfurther be imbedded in or secured to the barrier 12.

Each stiffening element can aid in securing segments of the barrier 12to surrounding tissues. The stiffening elements can have parts 307,including throughholes, notches, or other indentations for example, tofacilitate fixation of the stiffening element 300 to surrounding tissuesby any of a variety of fixation devices 306. These fixation devices 306can include screws, darts, dowels, or other suitable means capable ofholding the barrier 12 to surrounding tissue. The fixation devices 306can be connected either directly to the stiffening element 300 orindirectly using an intervening length of suture, cable, or otherfilament for example. The fixation device 306 can further be secured tothe barrier 12 near the stiffening element 300 without direct contactwith the stiffening element 300.

The fixation device 306 can be secured to or near the stiffening element300 at opposing ends of the length of the barrier 12 required to be insealing engagement with surrounding tissues. Alternatively, one or amultitude of fixation devices 306 can be secured to or near thestiffening element 300 at a readily accessible location that may not beat these ends. In any barrier 12 embodiment with an interior cavity 17and an opening 8 leading thereto, the fixation sites may be proximal tothe opening 8 to allow passage of the fixation device 306 and variousinstruments that may be required for their implantation.

FIGS. 53A and 53B illustrate one embodiment of a barrier 12incorporating the use of a stiffening element 300. The barrier 12 can bea plate and screw barrier 320. In this embodiment, the stiffeningelement 300 consists of two fixation plates, superior 310 and inferior312, an example of which is illustrated in FIGS. 54A and 54B with twoparts 308 passing through each plate. The parts 308 are located proximalto an opening 8 leading into an interior cavity 17 of the barrier 12.These parts 8 allow passage of a fixation device 306 such as a bonescrew. These screws can be used to secure the barrier means 12 to asuperior 50 and inferior 50′ vertebra. As the screws are tightenedagainst the vertebral endplate, the fixation plates 310, 312 compressthe intervening sealing means against the endplate along the superiorand inferior surfaces of the barrier 12. This can aid in creating asealing engagement with the vertebral endplates and prevent egress ofmaterials from within the disc 15. As illustrated in FIGS. 53A and 53B,only the superior screws have been placed in the superior plate 310,creating a sealing engagement with the superior vertebra.

FIGS. 55A and 55B illustrate another embodiment of a barrier 12 havingstiffening elements 300. The barrier 12 can be an anchor and rod barrier322. In this embodiment, the stiffening elements 300 consist of twofixation rods 304, an example of which is shown in FIGS. 56A and 56B,imbedded within the barrier 12. The rods 304 can include a superior rod314 and an inferior rod 316. Sutures 318 can be passed around these rods314 and 316 and through the barrier means 10. These sutures 318 can inturn, be secured to a bone anchor or other suitable fixation device 306to draw the barrier 12 into sealing engagement with the superior andinferior vertebral endplates in a manner similar to that describedabove. The opening 8 and interior cavity 17 of the barrier 12 are notrequired elements of the barrier 12.

FIG. 57 illustrates the anchor and rod barrier 322, described above,with fixation devices 306 placed at opposing ends of each fixation rod316 and 318. The suture 18 on the left side of the superior rod 318 hasyet to be tied.

Various methods may be employed to decrease the forces necessary tomaneuver the barrier 12 into a position along or within the lamellae ofthe annulus fibrosis 10. FIGS. 58A, 58B, 59A and 59B depict twopreferred methods of clearing a path for the barrier 12.

FIGS. 58A and 58B depict one such method and an associated dissectordevice 454. In these figures, the assumed desired position of theimplant is along the posterior annulus 452. In order to clear a path forthe implant, a hairpin dissector 454 can be passed along the intendedimplantation site of the implant. The hairpin dissector 454 can have ahairpin dissector component 460 having a free end 458. The dissector canalso have an advancer 464 to position the dissector component 460 withinthe disc 15. The dissector 454 can be inserted through cannula 456 intoan opening 462 in the annulus 10 along an access path directedanteriorly or anterior-medially. Once a free-end 458 of the dissectorcomponent 460 is within the disc 15, the free-end 458 moves slightlycausing the hairpin to open, such that the dissector component 460resists returning into the cannula 456. This opening 462 can be causedby pre-forming the dissector to the opened state. The hairpin dissectorcomponent 460 can then be pulled posteriorly, causing the dissectorcomponent 460 to open, further driving the free-end 458 along theposterior annulus 458. This motion clears a path for the insertion ofany of the implants disclosed in the present invention. The body ofdissector component 460 is preferably formed from an elongated sheet ofmetal. Suitable metals include various spring steels or nickel titaniumalloys. It can alternatively be formed from wires or rods.

FIGS. 59A and 59B depict another method and associated dissector device466 suitable for clearing a path for implant insertion. The dissectordevice 466 is shown in cross section and consists of a dissectorcomponent 468, an outer cannula 470 and an advancer or inner push rod472. A curved passage or slot 474 is formed into an intradiscal tip 476of outer cannula 470. This passage or slot 474 acts to deflect the tipof dissector component 468 in a path that is roughly parallel to thelamellae of the annulus fibrosis 10 as the dissector component 468 isadvanced into the disc 15 by the advancer. The dissector component 468is preferably formed from a super elastic nickel titanium alloy, but canbe constructed of any material with suitable rigidity and straincharacteristics to allow such deflection without significant plasticdeformation. The dissector component 468 can be formed from an elongatedsheet, rods, wires or the like. It can be used to dissect between theannulus 10 and nucleus 20, or to dissect between layers of the annulus10.

FIGS. 60A-C depict an alternate dissector component 480 of FIGS. 59A and59B. Only the intradiscal tip 476 of device 460 and regions proximalthereto are shown in these figures. A push-rod 472 similar to that shownin FIG. 59A can be employed to advance dissector 480 into the disc 15.Dissector 480 can include an elongated sheet 482 with superiorly andinferiorly extending blades (or “wings”) 484 and 486, respectively. Thissheet 482 is preferably formed from a metal with a large elastic strainrange such as spring steel or nickel titanium alloy. The sheet 482 canhave a proximal end 488 and a distal end 490. The distal end 490 canhave a flat portion which can be flexible. A step portion 494 can belocated between the distal end 490 and the proximal end 488. Theproximal end 488 can have a curved shape. The proximal end can alsoinclude blades 484 and 486.

In the un-deployed state depicted in FIGS. 60A and 60B, wings 484 and486 are collapsed within outer cannula 470 while elongated sheet 482 iscaptured within deflecting passage or slot 474. As the dissectorcomponent 480 is advanced into a disc 15, passage or slot 478 directsthe dissector component 480 in a direction roughly parallel to theposterior annulus (90 degrees to the central axis of sleeve 470 in thiscase) in a manner similar to that described for the embodiment in FIGS.59A and 59B. Wings 484 and 486 open as they exit the end of sleeve 470and expand toward the vertebral endplates. Further advancement ofdissector component 480 allows the expanded wings 484 and 486 to dissectthrough any connections of nucleus 20 or annulus 10 to the endplatesthat may present an obstruction to subsequent passage of the implants ofthe present invention. When used to aid in the insertion of a barrier,the dimensions of dissector component 480 should approximate those ofthe barrier such that the minimal amount of tissue is disturbed whilereducing the forces necessary to position the barrier in the desiredlocation.

FIGS. 61A-61D illustrate a method of implanting a disc implant. A discimplant 552 is inserted into a delivery device 550. The delivery device550 has a proximal end 556 and a distal end 558. The distal end 558 ofthe delivery device 550 is inserted into an annulotomy illustrated inFIG. 61A. The annulotomy is preferably located at a site within theannulus 10 that is proximate to a desired, final implant 552 location.The implant 552 is then deployed by being inserted into the disc 15through the distal end 558 of the delivery device 550. Preferably theimplant is forced away from the final implant location, as shown in FIG.61B. An implant guide 560 can be used to position the implant 552. Afterdeployment of the implant 552, an augmentation material 554 can beinjected into the disc 15, shown in FIG. 61C. The augmentation material554 can include a hydrogel or collagen, for example. In one embodiment,the delivery device 550 is removed from the disc 15 and a separate tubeis inserted into the annulotomy to inject the augmentation material 554.Alternately, the distal end 558 of the delivery device 550 can remainwithin the annulotomy and the augmentation material 554 injected throughthe delivery device 550. Next, the delivery device 550 is removed fromthe annulotomy and the intradiscal implant 552 is positioned over theannulotomy in the final implant location, as shown in FIG. 61D. Theimplant 552 can be positioned using control filaments described above.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A method of reinforcing an annulus of an intervertebral disccomprising: providing a biocompatible support member, wherein at least aportion of said biocompatible support member is concave; and implantingthe biocompatible support member along an innermost surface of theannulus, wherein said biocompatible support member extends along aninterior aspect of the annulus, and wherein said biocompatible supportmember is entirely disposed along said aspect, thereby reinforcing theannulus.
 2. The method of claim 1, further comprising the step ofanchoring the biocompatible support member to the annulus.
 3. The methodof claim 1, further comprising the steps of attaching the biocompatiblesupport member to a connector and anchoring the connector to a wall ofthe annulus.
 4. The method of claim 1, further comprising the steps ofattaching the biocompatible support member to a connector and anchoringthe connector to a vertebral endplate.
 5. The method of claim 1, furthercomprising the step of attaching a connector to a wall of the annulus,wherein said connector is coupled to said support member.
 6. The methodof claim 1, further comprising the step of attaching a connector to avertebral endplate, wherein said connector is coupled to saidbiocompatible support member.
 7. The method of claim 1, furthercomprising displacing a herniated annulus segment to approximately itspre-herniated location.
 8. The method of claim 1, wherein the step ofproviding a biocompatible support member comprises providing a barrier.9. The method of claim 1, wherein the step of implanting thebiocompatible support member comprises placing said support member tosubstantially seal a defect in the intervertebral disc.
 10. The methodof claim 1, wherein the step of implanting said biocompatible supportmember comprises placing said support member to substantially close adefect in the annulus.
 11. The method of claim 1, further comprisingsecurely establishing the biocompatible support member to, within, orposterior to a herniated segment in the disc.
 12. The method of claim11, further comprising returning at least a portion of the herniatedsegment of the annulus to a site substantially within its pre-herniatedborders.
 13. The method of claim 1, further comprising distributingpressure within the disc space.
 14. The method of claim 1, furthercomprising facilitating tissue ingrowth of disc tissue.
 15. The methodof claim 1, further comprising providing augmentation material operableto augment the nucleus pulposus of the disc.